FSI Flashcards
octamer of histones + spiral/solenoid stability
h2a, h2b, h3 and h4
h1 binds nucleosome and linker DNA. may stabilize spiral/solenoid stuff through interaction with histone N terminal tails
where does HAT acetylate and how does it work
transfer acetyl to NH3+ group of lysine
removes the + charge on histones, decreasing strong interaction with - PO4 dna groups
“writer”
general transcription factors
locate tata, define start of transcription, recruit rna pol 2, low rate of transcription with no specificity, present in all cell nuclei
proximal promoter, consensus sequence
tata box
- meaning that it is found in a lot of things
- close to a promoter region
- binds specific transcription factors (tissue spec)
- approx 18-26 bases upstream
timing of transcription initiation specific factors
chromatin remodelling, histone mod, TBP finds tata, then TF2D, then B, E, H (general transcription factors that guide pol 2). guide the formation of the basal transcription complex
regulatory transcription factors
control rate of transcription, function as activators or repressors, often tissue specific
transcription process
tata box recognition, activation/dna binding/dimerization, a helix binds to groove bending dna and separating strands, basic/hydrophobic AA (leu) stabilize DNA binding
zinc finger motif transcription factor
zinc finger binds to specific motifs like 2 cys/2 his
- activation by ligands like hormones binding to receptor
- binds in major groove and forms a stretch of a helices
- zinc holds a helix and b sheet together. cluster of 3 that form in major groove and have a helix to connect. strong and specific
When it needs to open the DNA sequence, it needs tighter binding so you need more than one protein to accomplish this
dna binding domain in transcription factor
recognizes consensus dna sequence
-a helix with basic aa, lies in major or minor groove and contacts n bases (DIRECTLY), basic aa stabilize binding
- bend dna!
activation domain in transcription factor
interacts with other tx factors
domains of transcription factors
activation, dna binding, dimerization (from N to C terminus)
bzip
DNA binding: each subunit has 1 a helix. a helices with basic aa that contact n bases in major groove. basic aa stabilize them
dimerization: amphipathic a helix. dimerizes in coiled coil by hydrophobic interactions
ex. leucine zipper
leucine zipper dimerization domain
every 7th aa is leucine. heptad repeat
provides amphipathic a helix for dimerization
- other hydrophobic aa could replace leu
ap1 transcription factor
activator protein 1
- bzip protein!
- ubiquitous tx factor
- regulates gene expression in response to growth factors, stress, pathogens
- controls cell processes including differentiation and cell division
- activation domain interacts with other tfs
nuclear receptor family dimer proteins
- must be acticated by ligand binding (lipid sol hormones and vitamins)
- coordinate the response of many genes to a hormone signal
- enter by active diffusion and bind to intracell receptors
- receptors are conserved!
dna binding domain of GR
nuclear receptor family
- each subunit has 2 zinc fingers
- 1 a helix of 1 zinc finger lies in major grooce and binds to similar sequence in dna. thus its 2 half sites
- there’s a lever arm that moves
can activate many genes at once as long as they have the GRE
myogenesis
done by myoD, myf5 and myogenin
- HLH protein
- binds reg region in many muscle specific genes, conserved
bone formation
runx2
- binds to enhancers
- runt domain clamps the dna between c terminal tail in major groove and the wing in minor groove
- mutation is cleidocranial dysplasia
MRNA cap
xtra nuc added to 5’ end. 7 methyl guanosine. added by 5’ to 5’ tiphosphate bond
- added as primary transcript emerges (not encoded)
- increases stability and required for translation
- polio target, makes itself without CBP!
intron removal and ligation esterification
2 transesterification reactions
- 2’ OH of one site attacks the 5’ splice site
- 2’ OH is attached to 5’ site
3’ OH upstream attacks 3’ splice site
exons joined by ligation
intron removal, protein side
large RNP with small nuclear RNP that have specific small nuclear RNA that are complementary to consensus sequences in precursor rna
- help in poitioning the spliceosome on precursor rna
binding
- at 5’ end and branch point. then form spliceosome then 5’ site is cleaved, 3’ is cleaved
poly A tail
protien binds AAUAAA
- cleavage factors CFI and CFII cleave rna
- poly A polymerase adds poly A posttranscriptionally
- increases stability and translational efficiency
miRNA processing
transcribed by pol 2 or intron derived
- regulate post transcriptionally
- each mrna has many target sequences for miRNA
- first forms pri-mirna from pol 2 or intron by forming hairpin structure
- processed by drosha in nuc forming pre-miRNA
- dicer cuts it in cyto
one strand is selected, other is degraded. assemble them into microRNPS or miRISC (from argonaute family)
- reg dna expression by destabilizing mrna or interfering with translation
moving from transcription to translation in cyto
cap binding protein.
mRNA then associates with cap and poly a binding proteins to form mRNPs (aka exon junction complex). mRNPS are transported thru nuclear pore from 5’ end then the cap is removed and eIF4 initiation factor is added
5’ non coding region of mrna
determines translational efficiency
protein coding sequence mrna
aka open reading frame. starts at aug and stops at stop codon
3’ noncoding mrna
influences rna stability
ribozyme
28 s that catalyzes peptide bond formation
translation factors
to load aa on tRNA requires ATP, 2 gtp for binding tnra to ribosome and translocation
eIF is initation: bind iniation tRNA, bind mRNA cap and associate mRNA with 40s and unwind mRNA. need GTP
- eEF is elongation that delivers trna to a site, translocate ribosome
- termination factors make stuff fall off
translation binding steps
- eIF2 binds initiator tRNA
- initiation tRNA binds to small ribosomal subunit
- cap binding complex, eIF-4E, G binds mRNA
- complex of 40S subunit tRNA binds to 5’ end of mRNA
- complex scans mRNA until initiator tRNA finds first aug
- anticodon of initiator tRNA is complementary to AUG
- large ribosomal subunit joins to form 80s complex
- initator trna is in p site
stops by release factors
streptomycinn
changes shape of 30s trna so mrna is read wrong
tetracycline
stops trna anticodon reading of mrna codon
erythromycin
binds to 50 s rRna and prevents elongation
chloramphenicol
stops 50S rrna and inhibits peptide bond formation
secretory pathway
proteins that are synthesized on ribosomes associated with ER. include extracell matrix, growth factors/hormones, cell surface receptors
- KDEL
- need to retain stuff here since post trans mod happens
mitochondria signal sequence
the matrix is the longest one
- usually hydrophobic amphiphillic alpha helix binds to hydrophobic face of the receptor
- use tom and tim to get inside
ubiquitination
added on C terminus to lysine by e 1,2,3 and ligase. many ubiquitins added
- proteasome degrades them by using cap enzyme to bind, atp hydrolysis to unfold proteins and feed them into a cylinder that is digested by proteolytic enzymes
**cytoplasmic pathway! meaning if there are misfolded proteins in ER, they are translated back through the translocon for degradation in cyto
ubiquitination signals
hydrophobic region on protein sufface is a sign is misfolded
- cyclins have odd sequence after they are done their job
phosphorylation by kinase causes conformational change exposing recognition sequence
common lymphoid progenitor cell makes
b and t cell
bone marrow to lymph node
T mature in thymus, active in lymph, roam in blood and lymph
B mature in bone marrow
common myeloid progenitor cell makes
neb, mast cell, monocyte
bone marrow to blood then tissue
cytotoxic t cell
bind to MHC class 1 on infected cell
- cd8
- self destroy after binding pathogen by lysis or apoptosis
helper t cell
bind to MHC class 2 on APC
- cd4
- release cytokines to activate b and cytotoxic t cells
- mature in thymus
antigen presenting cells
bone marrow derived: dendritic cells (phago and pinocytosis, fly to lymph for apc, make cytokines), langerhans, macrophages, b cells
have both mhc 1 and 2!
b cell stays in lymph
**follicular dendritic cell found in lymph node
have costim markers such as cd80 (b7-1_and cd 86 (b7- 2)
- recognition phase
adaptive and innate both do it. involves dendritic cells that recognize pathogen, process antigen and present. nonspecific inflam
- effector or response phase
via cytokines, neutrophils, macrophages (innate), antibodies and effector t lymph (adaptive) eliminate antigen
proinflam cytokines
innate or adaptive, mostly macrophages
- involve IL 1,2,6
TNF 1, INF a, INFb
- upregulate inflam reactions
regulatory cytokines
immunosuppressive: IL 10 and TGF b reduce expression of costim receptors that inhibit immune cell growh and stop response using t cell stim then t reg stim
chemokines
chemotaxis. recruit phagocytes to site of inflam like neutrophil, macrophage, fibroblast using IL 8
adaptive immune
key is lymph and antibodies. not actie unless antigenic challenge with high specificity
b cell
- after apc up, t helper cell binds, secretes cytokines, activates b cell then does clonal expansion and antibody production
T helper and APC
- acp binds to t helper (MHC 2) OR t cytotoxic binds to MHC 1
antibody structure
binds antigen at specific recog site and its constant regions activate complement through the classical pathway
- variable regions at the ends of the Y
- 2 heavy chain and 2 short light chains held by disulfide bonds
IgG
smallest, most abundant, mostly in tissue but in blood too
IgM
first to be made by b cells in infection, pnetamer so biggest
igA
in secretions, forms dimers
igE
minute amounts, primarily involved in allergy. constant region interacts with basal and mast cells
igD
stays on B cell (receptor thing)
least found
ways that antibodies stop virus
- neutralize = physical block of pathogenic parts
- agglutination = clump by blocking epitopes
- tag for destruction = signal the complement, phago, NK
- precipitation = makes them insoluble
- inflam = triggers histamine so more immune cells move
- complement = pokes holes in cell by binding to antibody, cascade (classical pathway)
*opsonization is enhancing phagocytosis!
cystic fibrosis, sickle cell, phenylketonuria, congenital deafness and recessive blindness
autosomal revessive
3 ways of getting autosomal dominant disorder
hapoloinsufficiency (missing gene so make less), dominant negative effect (make a toxic protein that also blocks health protein), gain of function (make too much protein)
familial hypercholesterolemia
haplo
- insufficient product made for ldlr resulting in high cholesterol or even very high in homozygotes (heart attacks in childhood)
osteogenesis imperfecta
dominant negative. more than 50% decrease in protein activity because its blocked by toxin
achondroplasia
autosomal dom with gain of function
- fibroblast growth factor receptor 3 (FGFR3)
- membrane bound receptor for fibroblast in chondrocytes and osteoblasts to regulate bone growth
- it is negative inhibition of growth by stopping the prolif of chondrocytes that produce cart
- this means - effect on endochondral ossification
hemophilia
xlinked recessive
x linked dominant on pedigree
no male to male transition
- id between autosomal dominant inheritance
amelogenesis imperfecta gene defects
mutations in enamelin gene (ENAM) = autosomal dominant
- MMP20 = autosomal recessive
- amelogenin gene (AMELX) = x linked pattern where men are more severe than women
amelogenesis imperfecta symptoms
thin enamel, yellow teeth and weak, smaller and cracked teeth, tooth decay/loss, open bite malocclusion
chromosomal disorders
change in number or structure
- down syndrome is trisomy 21
- turner is monosomy of x. always female
complex inheritance
polygenic. environmental factors and many genes play a role
- tested using familial clustering (family vs population average) and rate of occurance between twins and full siblings
- cleft lip and palate
cleft lip and palate
- incomplete fusion of lip and palate
- asians, boys, unilateral is common
- genetics: number of relatives with it, wonky chromosomes, IRF6 mutations (normal formation of lips, palate skin)
- environmental: drugs, meds, nutrition, infection during preg or illness
polymorphism
- two or more varient forms of trait on one gene
- mutation in coding is rare and harmful, but noncoding is not hamful
- usually point mutations
- periodontal disease
periodontal disease
- polymorphism
- we all respond diff to meds because of microbiome, genetic and epigenetic, eco etc
- has to do with IL1 and IL6 that do inflam
- no testing other than probing depth and 2q1
hypodontia, supernumerary teeth, malocclusion, hereditary gingival fibromatosis, oral cancer
- missing 1-5 teeth
- usually with other disease like cleft lip, cleidocranial dysplasia (bone and tooth disease), garnder syndrome
- overbite is overlap btw upper and lower incisors, overjet is max first
- overproduction of collagen
- inherited mutations carry higher risk of cancer. fanconi anemia is rare recessive disorder that can increase risk
type 2 dia, sickle cell anemia, osteogenesis imperfecta, epidermolysis bullosa, amelogenesis imperfecta
- increase risk of perio disease
- vulnerable to infection, problems with anesthesia
- alterning bone and dentin
- blistering of mucosa, making oral health bad and hard for dentures
- enamel structure off
haplotype
set of alleles at two or more neighboring loci on one of the two homologous chromosomes
compound heterozygote
two different mutant allells of a gene, not one wild type and one mutant